SEPARATION OF TROPHIC NICHES BY DUNG BEETLES (COLEOPTERA, SCARABAEOIDEA) IN OVERLAPPING HABITATS

摘要

In heterogeneous landscapes, mammals deposit excrement non-randomly. In pastures, some dung is concentrated over small areas, several hundred square metres for resting places of sheep flocks, 0.5 - 2 m(2) for dung-heaps of wild rabbits. Fresh scattered sheep pellets and trampled dung from sheep resting places and from rabbit dung-heaps constitute distinct trophic niches exploited by distinct dung beetle communities. The organization of dung beetle assemblage of winter-deposited sheep pellets (climatic constraints) is very similar to the organization of dung-heaps and sheep resting-place assemblages (edaphic constraints). Each species assemblage corresponds to a nomocenose, an aggregate of organisms living together in a particular habitat with a log-normal or a log-linar distribution of abundance. The juxtaposition of the nomocenoses increases biotic diversity in heterogeneous landscapes.